Women (N = 16) were equally divided into two groups; one taking oral contraception (for at least six months) and the other not. Ss were tested on three occasions (menses, mid-cycle, and luteal phase). Each S performed one maximal isotonic strength test (1 RM) of the leg extensors. Each performed a test to exhaustion at 50% of 1 RM on each phase-test. EMG electrodes were placed on the rectus femoris.

Fatigue was significantly increased for both groups during ovulation.

Implication. Women may exhibit exercise fatigue more easily during ovulation.